Cellular Energetics: Enzymes, Cellular Respiration, and Photosynthesis

Comprehensive vocabulary flashcards covering enzyme regulation, metabolic thermodynamics, cellular respiration, fermentation, and photosynthesis mechanisms based on lecture notes.

Enzymes

Biological catalysts that speed up chemical reactions and lower activation energy without being consumed, exhibiting specificity for their substrates.

temp and ph impact on enzyme

above ideal temp: activity decreases until enzyme denatures below optimal temp: molecules move slower until enzyme inactive or denatured, above ideal pH: rate decreases a lower H plus concentration interferes with shape, below ideal pH: rate decreases a higher H plus concentration interferes with enzyme shape

who is photosynthesis done by and what type of rxn is it?

autotrophs/producsrs; endergonic because energy used and anabolic because large molecule produced

who breaks down carbs and what type of rxn is it?

both autotrophs/producers and heterotrophs/consumers break down carbs to produce ATP, catabolic bc large molecule broken down and exergonic because energy exits

Coenzymes

Organic activators (such as CoA) that stabilize an enzyme's active form by acting as carriers for chemical groups or electrons.

Cofactors

Inorganic or organic helper molecules (such as metal ions like iron or vitamins) that bind firmly to an enzyme to assist its catalytic function.

Competitive Inhibitors

Inhibitor molecules that attach directly to the enzyme's active site, preventing the substrate from binding.

Noncompetitive (Allosteric) Inhibitors

Inhibitors that bind to an enzyme at a site other than the active site, causing a conformational change that alters the shape of the active site.

Feedback Inhibition

A regulatory mechanism where the end product of a metabolic pathway binds to and inhibits an enzyme early in the pathway, stopping unnecessary continuation.

how is food used for energy?

The breakdown of molecules into smaller ones moves electrons from one molecule to another, and these electrons carry energy with them. therefore, that energy is stored in another bond, released as heat, or harvested to make ATP. also electrons move as part of an H atom

Endotherms

Organisms that generate heat primarily from within, possessing a high metabolic rate and consuming large amounts of food to maintain body temperature.

Ectotherms

Organisms that derive heat primarily from their external environment, maintaining a much lower metabolic rate.

Homeotherms

Organisms that maintain a stable, constant internal body temperature homeostasis.

Poikilotherms

Organisms whose internal body temperature varies widely with changes in the environment.

electron carriers

they move electrons by shuttling H atoms around (reducing FAD+ or 2+), these electrons help create an H grant, when electrons move down this gradient through ATP synthase, ATP is generated.

ATP

bond between the second and third phosphate is very high energy and so when broken down energy is released and ADP forms. The phosphate broken off attaches to another molecule and transfers energy to that molecule (phosphorylation)

Oxidation

A chemical reaction involving the addition of oxygen, removal of hydrogen, or loss of electrons, which is exergonic and releases energy.

Reduction

A chemical reaction involving the removal of oxygen, addition of hydrogen, or gain of electrons, which is endergonic and stores energy.

mitochondria structure

double membrane, energy, harvested, organelle, smooth outer membrane (cristae) , inner membrane space (fluid filled space filled btw membranes, matrix (inner fluid filled space), DNA/ribosomes, enzymes (free in matrix and membrane bound)

overview of cellular respiration

catabolic pathway, as glucose broken down in small rxns, electrons shuttled (by nadh) down ETC

1. glycolysis, 2.pyruvate oxidation, 3. krebs/citric acid cycle, 4. electron transport chain

Phosphorylation

The transfer of a phosphate group broken off from ATP to another molecule, thereby transferring energy to that molecule.

Glycolysis

An anaerobic catabolic pathway occurring in the cytoplasm that splits a 6-carbon glucose molecule into two 3-carbon pyruvate molecules, yielding a net of $2\,\text{ATP}$ and $2\,\text{NADH}$. can occur with or without 02.

energy investment of glycolysis

endogenic, invest some ATP, Glucose is phosphorylated, rearranged, and split into 2G3P molecules

energy payoff of glycolysis

exogenic, harvest, some ATP and NADH; G3P gives a H to NAD+ to make NADH, C3 P broken down into pyruvate, intermediate (PEP) donates a P to ADP to make ATP

Substrate-Level Phosphorylation

The direct synthesis of ATP catalyzed by an enzyme through the transfer of a phosphate group from an intermediate substrate (such as PEP) to ADP.

Pyruvate Oxidation

The transition stage of aerobic cellular respiration in the mitochondrial matrix where pyruvate is oxidized into Acetyl CoA, releasing $\text{CO}_2$ and producing NADH.

Krebs (Citric Acid) Cycle

A cyclic series of reactions in the mitochondrial matrix where Acetyl CoA combines with oxaloacetate to form citrate, generating a net of $2\,\text{ATP}$, $6\,\text{NADH}$, and $2\,\text{FADH}_2$ per glucose molecule.

Electron Transport Chain (ETC)

A sequence of electron carrier proteins located along the mitochondrial cristae that use high-energy electrons to pump $\text{H}^+$ ions into the intermembrane space, with oxygen serving as the final electron acceptor.

building proton gradient

h cleaved off of NADH and FADH2. electrons stripped off of H atoms and passed from 1 carrier to next in mitochondrial membrane, proton pumps in the inner membrane pump H+ across membrane into inter membrane space

electron carriers

electrons that were shipped from the H of NADH and FADH2 are passed to proteins and various mobile electron carriers s in the intermembrane. each step is exergonic/oxidation, each carrier more electronegative than next, oxygen is final electron accepter

ATP synthase

H plus gradient has been made which results in the diffusion of H+ through ATP synthase. as H plus ions are passed through the membrane part of the enzyme rotates, causing other parts of the enzyme to shift into its active form so that ADP and P can fit at the active site and we joined to make ATP.

Chemiosmosis

The process by which $\text{H}^+$ ions diffuse down their electrochemical gradient across a membrane through ATP synthase to power the synthesis of ATP.

Oxidative Phosphorylation

ATP synthesis driven by the energy released during the oxidation of electron carriers ($\text{NADH}$ and $\text{FADH}_2$) and subsequent chemiosmosis.

fermenation

keeps glycolysis going by regenerating NAD plus, occurs in the cytosol, no oxygen needed, creates ethanol, and carbon dioxide, or lactate, two ATP, performed by obligate aenerobes and facultative anaerobes

respiration

releases energy from the breakdown of food with O2, occurs in the mitochondria, oxygen required, produces CO2 H2O, and up to 32 ATP, performed by obligate aerobes and facultative anaerobes.

Lactic Acid Fermentation

An anaerobic process occurring in human muscle cells, fungi, and bacteria where pyruvate is converted into lactate to regenerate $\text{NAD}^+$ for glycolysis.

Alcohol Fermentation

An anaerobic pathway occurring in yeast and bacteria that converts pyruvate into ethanol and $\text{CO}_2$ in order to regenerate $\text{NAD}^+$.

Mesophyll

The middle tissue layer of a plant leaf where chloroplasts are primarily concentrated.

Stomata

Microscopic pores in the surface of a leaf that regulate gas exchange, allowing $\text{CO}_2$ to enter and $\text{O}_2$ to exit.

Thylakoid

A flattened, green sac-like membrane structure inside chloroplasts that stores chlorophyll and captures solar energy during the light reactions.

Stroma

The fluid-filled space surrounding thylakoids in chloroplasts, containing ribosomes and chloroplast DNA, and serving as the site for the Calvin cycle.

photosynthesis overview

convert sunlight, energy to chemical energy of food, plants and other autotrophs are the producer.

photo autotrophs: use light energy to make organic molecules

chemo autotrophs: use chemicals in the Environment to make organic molecules

heterotrophs: consume organic molecules from other organisms for energy

light rxn

White energy converted into ATP/NADPH using electrons from H2O. use photo systems which are a cluster of pigment molecules, bound to proteins, along with a primary electron acceptor

H2O + light —> ATP + NADPH + O2

calvin cycle/light independent

occurs in stroma of chloroplast, takes the newly made ATP to power chemical reactions, converting CO2 and H from H2O into glucose, also produces G3P and uses NADPH and CO2.

1. carbon fixation: carbon dioxide fixed into carbohydrate by enzyme rubisco

2. reduction: 6 ATP and 6 NADPH used to make 6 G3P molecules. ADP AND NADPH go back to light rxns to be reused

3. regeneration: 1 G3P leaves the cycle, other 5 used to regenerate RUBP so that another carbon dioxide can be fixed into a carbohydrate

Chlorophyll a

The primary blue-green photosynthetic pigment that participates directly in the light reactions by converting solar energy into chemical energy.

Carotenoids

Yellow-orange accessory pigments that broaden the spectrum of light absorbed for photosynthesis and provide photoprotection.

Photosystem II

The pigment-protein complex that absorbs light optimally at a wavelength of $680\,\text{nm}$, acts first in the light reactions, and provides the energy to produce ATP.

Photosystem I

The pigment-protein complex that absorbs light optimally at a wavelength of $700\,\text{nm}$ and provides reducing power to generate NADPH.

Non-Cyclic Photophosphorylation

The linear electron pathway through Photosystems II and I that generates both chemical energy as ATP and reducing power as NADPH.

Cyclic Photophosphorylation

An alternative photosynthetic electron pathway where electrons cycle back through the transport system, producing extra ATP without generating NADPH.

Rubisco

The enzyme in the Calvin cycle responsible for carbon fixation, catalyzing the addition of $\text{CO}_2$ to a carbohydrate intermediate.

G3P (Glyceraldehyde 3-Phosphate)

An energy-rich 3-carbon sugar produced as the primary end product of the Calvin cycle, serving as the precursor for glucose, lipids, amino acids, and nucleic acids.